\(\Delta ABC,\text{Â}=90\text{đ}\text{ộ},\text{đ}\text{ư}\text{ờ}ng-caoAH,trung-tuy\text{ế}nBM,ph\text{â}n-gi\text{á}cCDc\text{ắ}t\)
\(nhau-t\text{ạ}i-c\text{ù}ng1\text{đ}i\text{ể}m.\)
\(CMR:a,\frac{BH}{HC}.\frac{CM}{MA}.\frac{AD}{BD}=1\)
\(b,BH=AC\)